Method and apparatus for measuring moving picture response curve

ABSTRACT

A picture is scrolled on a display  5  to be measured, and the scrolling moving picture is pursuit-captured by a color camera  3  so as to obtain a pursuit-captured moving picture image. A moving picture response curve using received light intensity data obtained based upon the pursuit-captured moving picture image is converted into a color moving picture response curve using emission intensity of display elements of the display  5  to be measured. The coloration of an edge part of the pursuit-captured moving picture image is decomposed into the respective color components, by which objective quantitative evaluations of color shifting can be made.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method and apparatus for measuring amoving picture response curve based upon an image of a moving picture ona display to be measured (also referred to as the “target display”) thatis captured by a moving picture color camera.

2. Description of Related Art

In order to evaluate the blurriness of a moving picture (also referredto as “moving picture blur”) on a display, measurements need to be madeby moving a camera so as to pursue the moving picture like humaneyeballs.

There is a known device (which is referred to as “moving picturecamera”) for capturing pursued images of a moving picture by rotating agalvanometer scanner provided with a mirror in accordance with themoving speed of the moving picture.

This image capturing device captures pursued images of a picture whilethe picture is scrolled from left to right. A graph is plotted byconverting CCD pixels in the moving direction of the captured image intoa time axis as the abscissa, and taking RGB received intensity as theordinate. The resultant curve is referred to as an MPRC (Moving PictureResponse Curve). Based on the edge shape of this MPRC, an MPRT (MovingPicture Response Time) is determined. Objective evaluations of themoving picture blurs can be made using this MPRT.

When a moving picture response curve is obtained as a result ofpursuit-capturing a moving picture by a color camera, a colorationphenomenon is observed at the edge part.

It has been known that, in the case of a field sequential drive displayfor example, in its principles, the light emitting timings for theelements of the respective colors are shifted for each RGB, so that acoloration phenomenon (which is called “color breakup”) occurs at theedge part of the displayed moving picture. This is because the displaytimings are shifted even though the moving picture response time is thesame for each color.

In the cases of plasma displays and liquid crystal displays, colorblurring occurs because the moving picture response time variesdepending on the color of each display element. For example, in a plasmadisplay, due to the differences in response speed and persistence of aphosphor among RGB colors, a bluish tone appears during a black to whitetransition, and a yellowish tone appears during a white to blacktransition. For this reason, color breakup occurs at the moving pictureedge part.

Thus, in performing a comparative evaluation between displays, it isdesired to obtain a moving picture response curve for every lightingcolor of a target displays.

It is an object of the present invention to provide a method ofmeasuring a moving picture response curve that enables objective andquantitative evaluations of color shifting by decomposing the colorationat an edge of a pursuit-captured moving picture image into therespective component colors.

SUMMARY OF THE INVENTION

Coloration (color breakup) at an edge of a display largely depends ongaps between light emission timings of the display. In order to modifythe color shifting at the edge part, information on the light emissiontimings of the display is necessary. Accordingly, display developersneed to identify the MPRC of the display for adjustment.

A method of measuring a moving picture response curve according to thepresent invention comprises the steps of: scrolling a picture on adisplay to be measured; pursuit-capturing (pursuing and capturing) thescrolling moving picture by a color camera to obtain a pursuit-captured(pursued and captured) moving picture image; and converting a movingpicture response curve using received light intensity data obtainedbased upon the pursuit-captured moving picture image into a movingpicture response curve using emission intensity of display elements ofthe display to be measured.

In this method, by measuring an edge of a moving picture shown on thedisplay through the moving picture pursuit color camera, the pursuedmoving picture is measured in the form of a color image. Measuring themoving picture in the form of a color image enables reproduction of animage viewed by human eyes.

In particular, since a moving picture response curve using receivedlight intensity data is converted into a moving picture response curveusing emission intensity of display elements of the display to bemeasured in the present invention, conversion into the moving pictureresponse curve using emission intensity of display elements of thedisplay to be measured can be accomplished irrespective of thecharacteristics of the color camera. It is therefore possible to makequantitative evaluations of color shifting of the display to bemeasured.

It is also possible to obtain a moving picture response curve usingchromaticity by converting the received light intensity data obtainedbased on the pursuit-captured moving picture image into chromaticity,and then the moving picture response curve using chromaticity isconverted into a moving picture response curve using emission intensityof display elements of the display to be measured.

Further, the moving picture response curve using the received lightintensity data obtained based on the pursuit-captured moving pictureimage may be converted directly into a moving picture response curveusing emission intensity of display elements of the display to bemeasured.

An apparatus for measuring a moving picture response curve issubstantially the same invention as the foregoing method of themeasuring moving picture response curve according to the presentinvention.

These and other advantages, features and effects of the presentinvention will be made apparent by the following description ofpreferred embodiments with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating a construction including a movingpicture pursuit color camera.

FIG. 2 is a light path diagram illustrating a positional relationshipbetween a detection surface of a camera and a display device to bemeasured.

FIG. 3( a) is a view illustrating a measurement pattern P moving at aspeed vp indicated by an arrow and a field of view corresponding to acamera detection surface moving at a movement speed vc to pursuethereafter.

FIG. 3( b) is a graph showing a luminance distribution of a measurementpattern P detected at the camera detection surface.

FIG. 3( c) is a graph showing a luminance distribution of themeasurement pattern P where an image of the measurement pattern P iscaptured with a minimum blur.

FIG. 4 is a flowchart illustrating a procedure for determiningchromaticity correction coefficient and display chromaticitycoefficient.

FIG. 5 is a flowchart illustrating a flow of converting a measurementvalue of a color camera 3 into a color moving picture response curveusing chromaticity, and into a color moving picture response curve usingemission intensity of the display elements of the display of measuringobject.

FIG. 6 is a flowchart illustrating a flow of conversion from measurementdata according to another embodiment.

FIG. 7 shows an image of a pursued and captured (referred to as“pursuit-captured”) moving picture measured by the color camera 3.

FIG. 8 is a graph showing color moving picture response curves using RGBreceived light intensity of the color camera 3.

FIG. 9 is a graph showing color moving picture response curves usingchromaticity.

FIG. 10 is a graph showing moving color moving picture response curvesusing emission intensity of the display.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 is a block diagram illustrating a construction including a movingpicture pursuit color camera.

The moving picture pursuit color camera photographs the screen of adisplay 5 to be measured, which includes a galvanometer mirror 2, acolor camera 3 for photographing the display 5 through the galvanometermirror 2, a photosensor 11 and a computer control section 6.

The galvanometer mirror 2 includes a permanent magnet disposed rotatablyin a magnetic field that is generated by applying electric current to acoil, and is capable of rotating smoothly and rapidly.

A rotation drive signal is transmitted from the computer control section6 to the galvanometer mirror 2 through a galvanometer mirror drivecontroller 7.

Instead of providing the galvanometer mirror 2 and the color camera 3separately, a camera such as a light-weight digital camera may bedisposed on a spin base so as to be rotationally driven by a rotationaldrive motor.

The color camera 3 has a field of view including a part of or the entiredisplay 5.

A luminous efficiency film 9 and the galvanometer mirror 2 are presentbetween the color camera 3 and the display 5 so that the field of viewof the color camera 3 can move in one dimensional direction (hereinafterreferred to as “scroll direction”) on the display 5 in response to therotation of the galvanometer mirror 2.

The photosensor 11 detects an image moving on the display 5, and therotation of the galvanometer mirror 2 is triggered to start at the timeof detection by the photosensor 11. The photosensor 11 may be spared,and in that case, a trigger signal that states the rotation of thegalvanometer mirror 2 may be transmitted from the computer controlsection 6 to the galvanometer mirror drive controller 7.

Image signals obtained from the color camera 3 are taken into thecomputer control section 6 through I/O board 8.

A liquid crystal monitor 10 is connected to the computer control section6.

FIG. 2 is a light path diagram illustrating the positional relationshipbetween a detection surface 31 of the color camera 3 and the display 5to be measured. Light rays from the display 5 are reflected by thegalvanometer mirror 2 to be incident on the lens of the color camera 3and detected at the detection surface 31 of the color camera 3. A mirrorimage 32 of the detection surface 31 of the color camera 3 is drawn inbroken lines on the rear side of the galvanometer mirror 2.

Let the distance along the optical path between the display 5 and thegalvanometer mirror 2 be represented by L, the distance along theoptical path between the display 5 and the lens be represented by a, andthe distance along the optical path between the lens and the detectionsurface 31 be represented by b. When the focal distance f of the lens isgiven, the relationship between a and b can be determined using thefollowing equation:1/f=1/a+1/b

Assume that a coordinate of the screen 5 of the display device to bemeasured in the scrolling direction is X, and that a coordinate in termsof received light intensity of the detector plane 31 of the color camera3 is Y. Set X0, the origin of X, at the center of the screen of thedisplay to be measured, and set Y0, the origin of Y, at the pointcorresponding to X0. If the magnification of the lens of the camera 3 isM,X=MYis satisfied. The magnification M is expressed using the aforesaid a andb as follows:M=−b/a

If the galvanometer mirror 2 is rotated by an angle φ, the correspondingposition on the display 5 to be measured deviates with respect to therotation axis of the galvanometer mirror 2 by an angle of 2φ. Thecoordinate X on the display 5 to be measured that corresponds to theangle 2φ is expressed as follows:X=L tan 2φ

A modification of the equation above gives the following equation:Φ=arctan(X/L)/2

The equation [X=L tan 2φ] is differentiated by time to give thefollowing equation:v=2Lω cos⁻²(2φ)where v represents movement speed of the field of view 33 on thedisplay, and ω represents rotation viewing angular speed of thegalvanometer mirror (ω=dφ/dt). If φ is a minute angle, cos²(2φ)→1 can beassumed, therefore the equation above can be expressed as:ω=v/2L

Thus, it can be assumed that the movement speed v of the field of view33 on the display is proportional to the rotation viewing angular speedω of the galvanometer mirror 2.

Now, referring to FIGS. 3( a)-3(c), the principles of a method ofevaluating a display will be described.

Suppose that a measurement pattern P for evaluation is a band-likemeasurement pattern P having a luminance brighter than the backgroundand extends in the scroll direction over a predetermined length. Whenthe galvanometer mirror 2 is rotated at a viewing angular speedcorresponding to the movement of the measurement pattern P on thedisplay 5 to be measured, an image of the measurement pattern P iscaptured by the color camera 3. However, note that the shutter of thecolor camera 3 is kept open during the rotation of the galvanometermirror 2.

FIG. 3( a) is a view illustrating a measurement pattern P moving at aspeed vp indicated by an arrow and a field of view 33 corresponding tothe camera detection surface 31 moving at a movement speed vc to pursuethereafter.

Receiving light intensity distributions of images detected at the cameradetection surface 31 are as shown in FIGS. 3( b) and 3(c). The abscissain FIG. 3( a), 3(b) represents pixel aligned along the scroll direction,and the ordinate represents received light intensity.

FIG. 3( b) shows an image of the measuring pattern P when the movementspeed vc of the field of view 33 does not correspond to the movementspeed vp of the measuring pattern P.

When the rotation viewing angular speed of the galvanometer mirror 2 isrepresented by ω and the rotation viewing angular speed corresponding tothe movement speed vp of the measurement pattern P is designated as ω 0,the movement speed vc of the field of view 33 equals to the movementspeed vp of the measurement pattern P. FIG. 3( c) shows an image of themeasurement pattern P when the movement speed vc of the field of view 33corresponds to the movement speed vp of the measurement pattern P.

Next, the relationship between a moving picture response curve (MPRC)and a moving picture response time (MPRT) will be described.

The received light intensity distribution of the image of themeasurement pattern P detected by the camera detection surface 31 asdescribed above (FIG. 3( b), FIG. 3( c)) is defined as the movingpicture response curve MPRC. A coordinate in pixel of the color camera 3is expressed y as described above.

Simply stated, the moving picture response time (MPRC) is a curveobtained by converting the abscissa y of the moving picture responsecurve (MPRC) into time axis.

Where the ratio of the number of pixels of the display 5 of the targetdisplay to the number of pixels of the camera detection surface 31corresponding to the display 5 is defined as R, the ratio R isrepresented by:R=(Pi _(PDP) /Pi _(CCD))M _(OPT)wherein the subscript “PDP” indicates the target display (the targetdisplay is not limited to the PDP in the present invention), and thesubscript “CCD” indicates the detection surface of the camera (thecamera is not limited to the CCD in the present invention) Further,Pi_(PDP) is the pixel pitch of the target display, Pi_(CCD) is the pixelpitch of the detection surface of the color camera 3, and M_(OPT) is themagnification of the camera 3 (M_(OPT) is equal to the magnification Mdescribed above).

A relationship between the coordinate X_(PDP) on the target display 5and the pixel coordinate y of the camera 3 (obtained by converting thecoordinate Y on the detection surface of the camera 3 into the number ofpixels) is represented by:X _(PDP)=(Pi _(PDP) /R)y

The viewing angle θ of the coordinate X_(PDP) is represented by:θ=arctan(X _(PDP) /a)where a is the distance between the target display and the lens asdescribed above.

Where a viewing angular speed on the target display 5 is defined as Vθ,a relationship between the viewing angular speed Vθ and a speed (dy/dt)along the pixels on the detection surface of the color camera 3 isrepresented by:Vθ=dθ/dt=(1/a)(dX _(PDP) /dt)=(Pi _(PDP) /aR)dy/dt

However, this equation is an approximate expression when a issufficiently great. Where the viewing angular speed Vθ is constant, thenumber of pixels on the detection surface of the color camera 3 and thetime can be correlated with each other by this equation. Where a changein the number of pixels on the detection surface of the color camera 3is defined as Δy and a change in time is defined as Δt, the followingequation is established:Δy=(aRVθ/Pi _(PDP))Δt

With this equation, the blur of the image on the detection surface ofthe camera 3 can be converted into a time span. Therefore, a curveresulting from conversion of the abscissa y of the moving pictureresponse curve (MPRC) which is the luminance distribution of the imageof the measurement pattern P detected by the camera detection surface 31into the time t, that is, a moving picture response time (MPRT) can beobtained.

Next, the principles of the process for obtaining a color moving pictureresponse curve according to the present invention are discussed.

A pursuit-captured color moving picture is an image that twodimensionally shows intensity of received light (referred to as “RGBreceived light intensity” in this specification) that transmits throughRGB filters of the installed color camera 3 and is detected by sensorpixel.

The first attempt is to convert the RGB received light intensity of animage detected by the color camera 3 into chromaticity. The conversionequation is as follows:

$\begin{matrix}{{\begin{bmatrix}{KXR} & {KXG} & {KXB} \\{KYR} & {KYG} & {KYB} \\{KZR} & {KZG} & {KZB}\end{bmatrix}*\begin{bmatrix}{CCDR} \\{CCDG} \\{CCDB}\end{bmatrix}} = \begin{bmatrix}{CCDX} \\{CCDY} \\{CCDZ}\end{bmatrix}} & \left\lbrack {{eq}.\mspace{14mu} 1} \right\rbrack\end{matrix}$where the following [eq. 2] represents “chromaticity correctioncoefficients” for converting RGB received light intensity of therespective RGB color filters of the color camera 3 into chromaticity.

$\begin{matrix}\begin{bmatrix}{KXR} & {KXG} & {KXB} \\{KYR} & {KYG} & {KYB} \\{KZR} & {KZG} & {KZB}\end{bmatrix} & \left\lbrack {{eq}.\mspace{14mu} 2} \right\rbrack\end{matrix}$

The following [eq. 3] represents intensity values of RGB received lighttransmitting through the RGB filters of the color camera 3.

$\begin{matrix}\begin{bmatrix}{CCDR} \\{CCDG} \\{CCDB}\end{bmatrix} & \left\lbrack {{eq}.\mspace{14mu} 3} \right\rbrack\end{matrix}$

The following [eq. 4] represents chromaticity obtained from the colorcamera 3.

$\begin{matrix}\begin{bmatrix}{CCDX} \\{CCDY} \\{CCDZ}\end{bmatrix} & \left\lbrack {{eq}.\mspace{14mu} 4} \right\rbrack\end{matrix}$

According to eq. 1, the chromaticity of the target display (eq. 4) canbe determined from the chromaticity correction coefficients (eq. 2) andthe RGB received light intensity (eq. 3). While the chromaticity (eq. 4)is expressed using XYZ, it is also possible to convert from XYZ intochromaticity parameters such as Y, x, y or L, u′, v′ or the like.

The foregoing chromaticity correction coefficients (eq. 2) is requiredto be determined previously.

The procedure for determining this chromaticity correction coefficientis now described referring to a flowchart (FIG. 4).

To determine a chromaticity correction coefficient, R color is displayedon a display (Step S1), an RGB received light intensity is measured by acolor camera 3 and a measurement value is written as CCDRr, CCDGr, andCCDBr (Step S2).

Then, a chromaticity of X, Y, Z on the R color display are measured by acolor luminance meter, and the resulting measurement is written as SXr,SYr, SZr (Step S3).

As well as in G color display on the display, CCD measurement CCDRg,CCDGg, CCDBg, and chromaticity measurement SXg, SYg, SZg measured withthe color luminance meter are determined in the same way as above.

As well as in B color display on the display, also CCD measurementCCDRb, CCDGb, CCDBb, and chromaticity measurement SXb, SYb, SZb measuredwith the color luminance meter are determined in the same way.

As a result, the following simultaneous equations with three unknownsare established:

$\begin{matrix}{{\begin{bmatrix}{KXR} & {KXG} & {KXB} \\{KYR} & {KYG} & {KYB} \\{KZR} & {KZG} & {KZB}\end{bmatrix}*\begin{bmatrix}{CCDRr} \\{CCDGr} \\{CCDBr}\end{bmatrix}} = \begin{bmatrix}\begin{matrix}{SXr} \\{SYr}\end{matrix} \\{SZr}\end{bmatrix}} & \left\lbrack {{eq}.\mspace{14mu} 5} \right\rbrack \\{{\begin{bmatrix}{KXR} & {KXG} & {KXB} \\{KYR} & {KYG} & {KYB} \\{KZR} & {KZG} & {KZB}\end{bmatrix}*\begin{bmatrix}{CCDRg} \\{CCDGg} \\{CCDBg}\end{bmatrix}} = \begin{bmatrix}\begin{matrix}{SXg} \\{SYg}\end{matrix} \\{SZg}\end{bmatrix}} & \left\lbrack {{eq}.\mspace{14mu} 6} \right\rbrack \\{{\begin{bmatrix}{KXR} & {KXG} & {KXB} \\{KYR} & {KYG} & {KYB} \\{KZR} & {KZG} & {KZB}\end{bmatrix}*\begin{bmatrix}{CCDRb} \\{CCDGb} \\{CCDBb}\end{bmatrix}} = \begin{bmatrix}\begin{matrix}{SXb} \\{SYb}\end{matrix} \\{SZb}\end{bmatrix}} & \left\lbrack {{eq}.\mspace{14mu} 7} \right\rbrack\end{matrix}$

Solving these three simultaneous equations gives chromaticity correctioncoefficients (eq. 2) including nine unknowns (Step S5).

At this time, the matrix (eq. 9) that consists of actual measurementvalues SXr, SYr, SZr, SXg, SYg, SZg, SXb, SYb, SZb for single colordisplay measured by the color luminance meter used in determining theforegoing chromaticity correction coefficient is stored (Step S6). Thismatrix is referred to as “display chromaticity coefficient”.

FIG. 5 is a flowchart illustrating a method for converting the RGBreceived light intensity measured by the color camera 3 into emissionintensity of display elements of the target display.

A scrolling image displayed on the display is pursued by thegalvanometer scanner, and the photosensor detects a measurement timing,upon which the color camera 3 pursuit-captures the image. This image isreferred to as “pursuit-captured color image”. The image data is inputinto the computer control section 6 (Step T1).

Based on the RGB received light intensity data, color moving pictureresponse curves (FIG. 8) are produced (Step T2).

Subsequently, the RGB received light intensity data are converted intochromaticity using the conversion equation (eq. 1) (Step T3). Thus, thechromaticity CCDX, CCDY, CCDZ can be determined from the measurementvalue of the RGB received light intensity of the color camera 3.

Color moving picture response curves using the chromaticity are drawn(Step T4).

On the other hand, the chromaticity CCDX, CCDY, CCDZ obtained from thecolor camera 3 are converted into RGB emission intensity of the targetdisplay (Step T5).

Since the transmittance of the color filter provided in the CCD is notadapted for single color of RGB of the display, a color moving pictureresponse curve of a color camera is different from an emission intensityresponse curve of the display. For example, since Green in a colorcamera has a wide band for transmissive wavelength, the color includes amixture of not only G of the display, but also R and B components. Forthis reason, the emission intensity is different from that of G of thedisplay, which makes it difficult to adjust the timing.

This conversion equation is expressed as follows:

$\begin{matrix}{{\left\lbrack {\begin{matrix}\begin{matrix}{SXr} \\{SYr}\end{matrix} \\{SZr}\end{matrix}\begin{matrix}\begin{matrix}{SXg} \\{SYg}\end{matrix} \\{SZg}\end{matrix}\begin{matrix}\begin{matrix}{SXb} \\{SYb}\end{matrix} \\{SZb}\end{matrix}} \right\rbrack*\begin{bmatrix}{DisplayR} \\{DisplayG} \\{DisplayB}\end{bmatrix}} = \begin{bmatrix}{CCDX} \\{CCDY} \\{CCDZ}\end{bmatrix}} & \left\lbrack {{eq}.\mspace{14mu} 8} \right\rbrack\end{matrix}$where [eq. 9] expressed as follows represents the foregoing displaychromaticity coefficients;

$\begin{matrix}\left\lbrack {\begin{matrix}\begin{matrix}{SXr} \\{SYr}\end{matrix} \\{SZr}\end{matrix}\begin{matrix}\begin{matrix}{SXg} \\{SYg}\end{matrix} \\{SZg}\end{matrix}\begin{matrix}\begin{matrix}{SXb} \\{SYb}\end{matrix} \\{SZb}\end{matrix}} \right\rbrack & \left\lbrack {{eq}.\mspace{14mu} 9} \right\rbrack\end{matrix}$

[eq. 10] expressed as follows represents display emission intensity tobe determined;

$\begin{matrix}\begin{bmatrix}{DisplayR} \\{DisplayG} \\{DisplayB}\end{bmatrix} & \left\lbrack {{eq}.\mspace{14mu} 10} \right\rbrack\end{matrix}$and [eq. 11] expressed as follows represents chromaticity calculatedusing the conversion equation (eq. 1) based on the measurement of thecolor camera 3.

$\begin{matrix}\begin{bmatrix}{CCDX} \\{CCDY} \\{CCDZ}\end{bmatrix} & \left\lbrack {{eq}.\mspace{14mu} 11} \right\rbrack\end{matrix}$

When the conversion equation (eq. 8) is solved, the emission intensityof the RGB display elements (eq. 10) can be determined based on thechromaticity CCDX, CCDY, CCDZ obtained from the color camera 3.

Based on the emission intensity of the display elements of the display,color moving picture response curves (FIG. 10) are produced (Step T6).

Through this procedure, the measurement values of the color camera 3 areconverted into emission intensity of the display elements of the targetdisplay, by which color moving picture response curves using theemission intensity of the display elements of the target display can beobtained.

Another embodiment of the present invention will be described below.

In the foregoing embodiment, as described referring to the flowchart(FIG. 4), each chromaticity correction coefficient is determined bymeasuring chromaticity by means of a color luminance meter and based onthis, emission intensity of the display is determined.

However, emission intensity of the display can be determined by thefollowing method without using chromaticity.

According to the following method, a color moving picture response curvebased on emission intensity of the display elements can be determinedwithout using luminance/chromaticity correction coefficients.Accordingly, it is no longer necessary to determine chromaticitycorrection coefficient with a color luminance meter.

The relationship between RGB received light intensity measurement values(CCD) of the color camera 3 and RGB emission intensity values of thedisplay (Display) is mathematized using CCDRr, CCDGr, CCDBr, CCDRg,CCDGg, CCDBg, CCDRb, CCDGb, CCDBb (eq. 13) used in eq. 5-eq. 7.

The following simultaneous equations are established:

$\begin{matrix}{{\begin{bmatrix}{CCDRr} & {CCDRg} & {CCDRb} \\{CCDGr} & {CCDGg} & {CCDGb} \\{CCDBr} & {CCDBg} & {CCDBb}\end{bmatrix}*\begin{bmatrix}{DisplayR} \\{DisplayG} \\{DisplayB}\end{bmatrix}} = \begin{bmatrix}{CCDR} \\{CCDG} \\{CCDB}\end{bmatrix}} & \left\lbrack {{eq}.\mspace{14mu} 12} \right\rbrack\end{matrix}$where [eq. 13] below is referred to as “display intensity correctioncoefficient” of the color camera 3:

$\begin{matrix}\begin{bmatrix}{CCDRr} & {CCDRg} & {CCDRb} \\{CCDGr} & {CCDGg} & {CCDGb} \\{CCDBr} & {CCDBg} & {CCDBb}\end{bmatrix} & \left\lbrack {{eq}.\mspace{14mu} 13} \right\rbrack\end{matrix}$These display intensity correction coefficients can be determined bypreliminarily measuring the RGB color displays of the target display bythe color camera 3 and calculating the RGB components of the colorcamera 3. The following [eq. 14] represents emission intensity of thedisplay;

$\begin{matrix}\begin{bmatrix}{DisplayR} \\{DisplayG} \\{DisplayB}\end{bmatrix} & \left\lbrack {{eq}.\mspace{14mu} 14} \right\rbrack\end{matrix}$and [eq. 15] represents measured RGB received light intensity of thecolor camera 3:

$\begin{matrix}\begin{bmatrix}{CCDR} \\{CCDG} \\{CCDB}\end{bmatrix} & \left\lbrack {{eq}.\mspace{14mu} 15} \right\rbrack\end{matrix}$

Solving the equation (eq. 12) gives emission intensity (eq. 14) of thedisplay. Accordingly, emission intensity of the display can bedetermined directly without using chromaticity.

Next, determining chromaticity (CCD) of the display by calculating theproduct of emission intensity of the display (Display) and chromaticityof RGB display colors of the display is attempted.

$\begin{matrix}{{\begin{bmatrix}{SXr} & {SXg} & {SXb} \\{SYr} & {SYg} & {SYb} \\{SZr} & {SZg} & {SZb}\end{bmatrix}*\begin{bmatrix}{DisplayR} \\{DisplayG} \\{DisplayB}\end{bmatrix}} = \begin{bmatrix}{CCDX} \\{CCDY} \\{CCDZ}\end{bmatrix}} & \left\lbrack {{eq}.\mspace{14mu} 16} \right\rbrack\end{matrix}$where [eq. 17] below represents chromaticity values measured on therespective display colors of the display; [eq. 18] represents emissionintensity of the display; and [eq. 19] represents chromaticity obtainedfrom the color camera 3.

$\begin{matrix}\begin{bmatrix}{SXr} & {SXg} & {SXb} \\{SYr} & {SYg} & {SYb} \\{SZr} & {SZg} & {SZb}\end{bmatrix} & \left\lbrack {{eq}.\mspace{14mu} 17} \right\rbrack \\\begin{bmatrix}{DisplayR} \\{DisplayG} \\{DisplayB}\end{bmatrix} & \left\lbrack {{eq}.\mspace{14mu} 18} \right\rbrack \\\begin{bmatrix}{CCDX} \\{CCDY} \\{CCDZ}\end{bmatrix} & \left\lbrack {{eq}.\mspace{14mu} 19} \right\rbrack\end{matrix}$Through this procedure, chromaticity can also be obtained.

The flow of the foregoing conversion from measurement data is describedreferring to a flowchart (FIG. 6) as follows.

A scrolling image displayed on the display is pursued by thegalvanometer scanner, and the photosensor detects a measurement timing,upon which the color camera 3 captures the image. The image is referredto as “pursuit-captured color image”. The image data is input into thecomputer control section 6 (Step U1).

RGB received light intensity (eq. 15) is measured by the color camera 3(Step U2).

Emission intensity of the display (eq. 14) are determined using theconversion equation (eq. 12)(Step U3).

Color moving picture response curves are calculated based on theemission intensity of the display elements (Step U4).

Subsequently, chromaticity values (CCD) of the display are determinedusing the conversion equation (eq. 16) (Step U5).

Color moving picture response curves are drawn using chromaticity CCDX,CCDY, CCDZ (Step U6).

EXAMPLE

A pursuit-captured color moving picture of a moving edge was measured bya moving picture pursuit color camera. The measurement conditions wereas follows:

-   -   Sample: field sequential drive display    -   Edge image scroll speed: 8 pixel/frame    -   Camera shutter speed: 1/20 sec    -   Image signal: 720P (progressive)        The measured pursuit-captured image is shown in FIG. 7.

Changes in RGB received light intensity in the edge part can be seen bythis pursuit-captured color moving picture image. In other words, theabscissa is converted into time axis and the ordinate represents RGBreceived light intensity so that color moving picture response curvescan be drawn. FIG. 8 shows color moving picture response curves ofsensitivity of the color camera 3 obtained in such a way.

Since these data are based on the light receiving sensitivity of thecolor camera 3, they are different from RGB display components ofemission intensity of the display.

Therefore, conversion into chromaticity is performed. Multiplyingpreliminarily determined chromaticity correction coefficients by RGBreceived light intensities of the color camera 3 (eq. 1) giveschromaticities XYZ.

The following is an example where chromaticities XYZ is converted intobrightness Y and chromaticities u, v. Here, Y indicates Y in thechromaticities X, Y, Z. Chromaticities u′ and v′ can be determined bythe following equations.u′=4X/(X+15Y+Z)v′=9X/((X+15Y+Z)

FIG. 9 is a graph showing color moving picture response curves usingchromaticities Y u′, v′.

Since the color moving picture response curves using chromaticities Yu′, v′ show the luminance Y/chromaticities u′, v′ of the moving picture,coloration degrees of the edge part or the like can be evaluatedquantitatively. However, since the filter of a color camera has thecamera-specific transmittance and varies depending on the camera, theintensity also varies depending on the color camera, and thereforecomparisons between individual cameras are impossible by color movingpicture response curves of color cameras. Therefore, conversions intoreceived light intensity/chromaticity facilitate comparative inspectionsbetween different measurement devices.

Color moving picture response curves of chromaticities u′, v′ with flatprofiles show that there is no color blur in the edge part of the movingpicture. In this graph, peaks are observed in u′, v′ in the vicinity of80 msec. This shows that the moving picture on the display has colorbreakup in its edge part.

Subsequently, using display chromaticity coefficients (FIG. 9), RGBemission intensity of the display are determined from the chromaticitiesXYZ.

FIG. 10 shows color moving picture response curves based on transmittedlight intensities of the display obtained in the foregoing way.

The color breakup of the edge part of the moving picture is caused bydifference in response of the transmitted light intensities of thedisplay. Accordingly, adjustments can be made by checking the responsecurves of the transmitted light intensities of the display for improvingthe display.

1. A method of generating a moving picture response curve of a displaydevice, comprising the steps of: displaying a pattern on the displaydevice, the pattern moving at a scroll velocity; moving an opticalsystem at a camera velocity to direct first light, emitted from thedisplay device, to a color camera, the camera velocity being based onthe scroll velocity so as to obtain in the camera a still image of thepattern; generating light intensity data from the obtained image;determining camera correction parameters based on second light emittedfrom the display device; converting the light intensity data intoemission intensity data of the display device based on the cameracorrection parameters; and generating a moving picture response curveusing the emission intensity data.
 2. The method of claim 1, whereinconverting the light intensity data into the emission intensity datacomprises: converting the light intensity data into chromaticity databased on the camera correction parameters; and converting thechromaticity data into the emission intensity data.
 3. The method ofclaim 1, wherein the light intensity data, the chromaticity data, andthe emission intensity data comprise time sequence data.
 4. The methodof claim 3, wherein: the display device comprises a plurality of colorchannels, and the emission intensity data comprise emission data for thecolor channels.
 5. The method of claim 4, further comprising: convertingthe chromaticity data to the emission intensity data using a pluralityof display chromaticity coefficients of the display device.
 6. Themethod of claim 5, further comprising: generating the second light usingthe color channels, the second light being single-color light;generating a plurality of single-color images by capturing thesingle-color light using the camera; and determining the cameracorrection parameters using the single-color images.
 7. The method ofclaim 6, further comprising: generating single-color light intensityvalues from the single-color images; measuring, using a color luminancemeter, luminance values of the single-color light from the displaydevice; and determining the camera correction parameters based on thesingle-color intensity values and the luminance values.
 8. The method ofclaim 7, further comprising: determining the display chromaticitycoefficients of the display device based on the luminance values.
 9. Themethod of claim 8, further comprising: organizing the displaychromaticity coefficients and the camera correction parameters intomatrix form, respectively.
 10. The method of claim 9, furthercomprising: converting the light intensity data into the chromaticitydata by multiplying the light intensity data with the chromaticitycorrection coefficients.
 11. The method of claim 4, wherein the colorchannels comprise a red channel, a green channel, and a blue channel.12. The method of claim 11, further comprising generating the movingpicture response curves for the color channels of the display device.13. The method of claim 1, further comprising: converting the lightintensity data into the emission intensity data by solving a pluralityof linear equations for the emission intensity data.
 14. An apparatusfor generating a moving picture response curve of a display device,comprising: an optical system for pursuit-capturing an image of a movingpattern scrolling on a display device, the system including a colorcamera for generating light intensity data from the image; and aprocessor configured to: determine camera correction parameters based onlight emitted from the display device; convert the light intensity datainto emission intensity data of the display device based on the cameracorrection parameters; and generate a moving picture response curvebased on the emission intensity data.
 15. The apparatus of claim 14,further comprising a mirror configured to direct the light emitted fromthe display device to the camera.
 16. The apparatus of claim 15, whereinthe mirror further comprises a rotatable mount configured to rotate themirror in synchronism with the moving pattern.
 17. The apparatus ofclaim 16, further comprising a photosensor configured to detect amovement of the moving pattern and supply a rotation signal to therotatable mount.
 18. The apparatus of claim 16, wherein the processorsupplies, in response to a movement of the moving pattern, a rotationsignal to the rotatable means.
 19. The apparatus of claim 14, whereinthe processor is further configured to: convert the light intensity datainto chromaticity data based on the camera correction parameters; andconvert the chromaticity data into the emission intensity data based ona plurality of display chromaticity coefficients.
 20. The apparatus ofclaim 19, further comprising a color luminance meter configured tomeasure luminance values of single-color light emitted by the displaydevice, wherein: the camera is further configured to capture a pluralityof single-color images in response to the single-color light; and theprocessor is further configured to: generate single-color lightintensity values from the single-color images; determine the displaychromaticity coefficients of the display device based on the luminancevalues; and determine the camera correction parameters based on thesingle-color intensity values and the luminance values.